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Where do you have the vacuum advance plugged up for the distributor?
What port did you use on the carb?
There should be 4 vacuum ports, one on the side of the metering block just behind the front float bowl, two on the bottom of the front of the carb and on on the back of the bottom of the carb. The one on the side is a ported vacuum port and you may not use it, one of the front bottom ports is a smaller port for the distributor, and the bigger one is for the pcv valve. The one on the back bottom is for the vacuum port for the power brake booster.
If you have the distributor connected to the side, then you have no vacuum going to the distributor vacuum advance at idle and the timming is retarded to much and can cause the engine to diesel and not shut off right away.
Here is a pic of the bottom of the carb.